The radius is inline with the thumb. The radius on your right arm is on the left. The radius on the left arm is on the right side. The Ulna is on the under side of the arm. The Ulna does not move, the radius rotates.
Injuries- You can Fracture, break, or have a birth deformity in your Ulna and Radius
Treatment- If you break your ulna or your radius to heal it you can put it in a splint, sling, cast, Ice it, Put a heating pad on it, or you can go to physical therapy.
workouts- wrist curls, Grip and squeeze, and a roller cable.